Enhanced Produced Water Deoiling Using a Centrifugal Separator

Abstract

Objectives/Scope A field trial was conducted for deoiling produced water at a Saudi Aramco GOSP. The objective of the field trial was to prove the concept of the centrifugal separator and test its capabilities to deoil produced water at varying feed rates and inlet concentrations. Methods, Procedures, Process The centrifuge was fed from the common water outlet line of a gravity water oil separator. Samples were taken for oil-in-water measurement using ASTMD7678. The testing covered various flowrates and inlet concentrations, which were adjusted by manipulating upstream conditions. Several parameters were used to determine the adequacy: Outlet oil-in water content (expected significantly less than 50 mg/l) and sufficiently high separation efficiencies to achieve the specification Unit downtime due to trip and failure of the unit and due to filter/screen cleaning and replacement Results, Observations, Conclusions The feed rate was adjusted by manipulating a valve at the inlet of the separator. A sample at the inlet and outlet of the separator was taken at each flowrate and condition as per the test guideline. It was noticed that inlet oil-in-water concentrations to separator were mostly on-spec, with only a few of them above 100 mg/l, as a result of temporarily lowering the dehydrator interface level for the the trial. The following observations can be made based on the test run data: The outlet oil-in water met the spec, far exceeding expectations Oil in water removal efficiency varied significantly, varying from 65-90% depending on rate and inlet concentration There were no issues in terms of unit downtime related to trips and filter/screen plugging Novel/Additive Information This was the first trial for a Saudi Aramco field. The process was applied to a facility with tight emulsions and a challenging environment that requires a highly efficient deoiling process, which the centrifugal separation has proven to be. Potential applications for produced water treatment and waste water handling can be derived from the field trial result.